path: root/lib/sanitizer_common/sanitizer_linux_libcdep.cc

//===-- sanitizer_linux_libcdep.cc ----------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is shared between AddressSanitizer and ThreadSanitizer
// run-time libraries and implements linux-specific functions from
// sanitizer_libc.h.
//===----------------------------------------------------------------------===//

#include "sanitizer_platform.h"
#if SANITIZER_LINUX

#include "sanitizer_common.h"
#include "sanitizer_flags.h"
#include "sanitizer_linux.h"
#include "sanitizer_placement_new.h"
#include "sanitizer_procmaps.h"
#include "sanitizer_stacktrace.h"

#include <dlfcn.h>
#include <pthread.h>
#include <sys/prctl.h>
#include <sys/resource.h>
#include <unwind.h>

#if !SANITIZER_ANDROID
#include <elf.h>
#include <link.h>
#endif

namespace __sanitizer {

void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
                                uptr *stack_bottom) {
  static const uptr kMaxThreadStackSize = 1 << 30;  // 1Gb
  CHECK(stack_top);
  CHECK(stack_bottom);
  if (at_initialization) {
    // This is the main thread. Libpthread may not be initialized yet.
    struct rlimit rl;
    CHECK_EQ(getrlimit(RLIMIT_STACK, &rl), 0);

    // Find the mapping that contains a stack variable.
    MemoryMappingLayout proc_maps(/*cache_enabled*/true);
    uptr start, end, offset;
    uptr prev_end = 0;
    while (proc_maps.Next(&start, &end, &offset, 0, 0, /* protection */0)) {
      if ((uptr)&rl < end)
        break;
      prev_end = end;
    }
    CHECK((uptr)&rl >= start && (uptr)&rl < end);

    // Get stacksize from rlimit, but clip it so that it does not overlap
    // with other mappings.
    uptr stacksize = rl.rlim_cur;
    if (stacksize > end - prev_end)
      stacksize = end - prev_end;
    // When running with unlimited stack size, we still want to set some limit.
    // The unlimited stack size is caused by 'ulimit -s unlimited'.
    // Also, for some reason, GNU make spawns subprocesses with unlimited stack.
    if (stacksize > kMaxThreadStackSize)
      stacksize = kMaxThreadStackSize;
    *stack_top = end;
    *stack_bottom = end - stacksize;
    return;
  }
  pthread_attr_t attr;
  CHECK_EQ(pthread_getattr_np(pthread_self(), &attr), 0);
  uptr stacksize = 0;
  void *stackaddr = 0;
  pthread_attr_getstack(&attr, &stackaddr, (size_t*)&stacksize);
  pthread_attr_destroy(&attr);

  CHECK_LE(stacksize, kMaxThreadStackSize);  // Sanity check.
  *stack_top = (uptr)stackaddr + stacksize;
  *stack_bottom = (uptr)stackaddr;
}

// Does not compile for Go because dlsym() requires -ldl
#ifndef SANITIZER_GO
bool SetEnv(const char *name, const char *value) {
  void *f = dlsym(RTLD_NEXT, "setenv");
  if (f == 0)
    return false;
  typedef int(*setenv_ft)(const char *name, const char *value, int overwrite);
  setenv_ft setenv_f;
  CHECK_EQ(sizeof(setenv_f), sizeof(f));
  internal_memcpy(&setenv_f, &f, sizeof(f));
  return setenv_f(name, value, 1) == 0;
}
#endif

bool SanitizerSetThreadName(const char *name) {
#ifdef PR_SET_NAME
  return 0 == prctl(PR_SET_NAME, (unsigned long)name, 0, 0, 0);  // NOLINT
#else
  return false;
#endif
}

bool SanitizerGetThreadName(char *name, int max_len) {
#ifdef PR_GET_NAME
  char buff[17];
  if (prctl(PR_GET_NAME, (unsigned long)buff, 0, 0, 0))  // NOLINT
    return false;
  internal_strncpy(name, buff, max_len);
  name[max_len] = 0;
  return true;
#else
  return false;
#endif
}

#ifndef SANITIZER_GO
//------------------------- SlowUnwindStack -----------------------------------
#ifdef __arm__
#define UNWIND_STOP _URC_END_OF_STACK
#define UNWIND_CONTINUE _URC_NO_REASON
#else
#define UNWIND_STOP _URC_NORMAL_STOP
#define UNWIND_CONTINUE _URC_NO_REASON
#endif

uptr Unwind_GetIP(struct _Unwind_Context *ctx) {
#ifdef __arm__
  uptr val;
  _Unwind_VRS_Result res = _Unwind_VRS_Get(ctx, _UVRSC_CORE,
      15 /* r15 = PC */, _UVRSD_UINT32, &val);
  CHECK(res == _UVRSR_OK && "_Unwind_VRS_Get failed");
  // Clear the Thumb bit.
  return val & ~(uptr)1;
#else
  return _Unwind_GetIP(ctx);
#endif
}

struct UnwindTraceArg {
  StackTrace *stack;
  uptr max_depth;
};

_Unwind_Reason_Code Unwind_Trace(struct _Unwind_Context *ctx, void *param) {
  UnwindTraceArg *arg = (UnwindTraceArg*)param;
  CHECK_LT(arg->stack->size, arg->max_depth);
  uptr pc = Unwind_GetIP(ctx);
  arg->stack->trace[arg->stack->size++] = pc;
  if (arg->stack->size == arg->max_depth) return UNWIND_STOP;
  return UNWIND_CONTINUE;
}

static bool MatchPc(uptr cur_pc, uptr trace_pc) {
  return cur_pc - trace_pc <= 64 || trace_pc - cur_pc <= 64;
}

void StackTrace::SlowUnwindStack(uptr pc, uptr max_depth) {
  size = 0;
  if (max_depth == 0)
    return;
  UnwindTraceArg arg = {this, Min(max_depth + 1, kStackTraceMax)};
  _Unwind_Backtrace(Unwind_Trace, &arg);
  // We need to pop a few frames so that pc is on top.
  // trace[0] belongs to the current function so we always pop it.
  int to_pop = 1;
  /**/ if (size > 1 && MatchPc(pc, trace[1])) to_pop = 1;
  else if (size > 2 && MatchPc(pc, trace[2])) to_pop = 2;
  else if (size > 3 && MatchPc(pc, trace[3])) to_pop = 3;
  else if (size > 4 && MatchPc(pc, trace[4])) to_pop = 4;
  else if (size > 5 && MatchPc(pc, trace[5])) to_pop = 5;
  PopStackFrames(to_pop);
  trace[0] = pc;
}

#endif  // !SANITIZER_GO

static uptr g_tls_size;

#ifdef __i386__
# define DL_INTERNAL_FUNCTION __attribute__((regparm(3), stdcall))
#else
# define DL_INTERNAL_FUNCTION
#endif

void InitTlsSize() {
#if !defined(SANITIZER_GO) && !SANITIZER_ANDROID
  typedef void (*get_tls_func)(size_t*, size_t*) DL_INTERNAL_FUNCTION;
  get_tls_func get_tls;
  void *get_tls_static_info_ptr = dlsym(RTLD_NEXT, "_dl_get_tls_static_info");
  CHECK_EQ(sizeof(get_tls), sizeof(get_tls_static_info_ptr));
  internal_memcpy(&get_tls, &get_tls_static_info_ptr,
                  sizeof(get_tls_static_info_ptr));
  CHECK_NE(get_tls, 0);
  size_t tls_size = 0;
  size_t tls_align = 0;
  get_tls(&tls_size, &tls_align);
  g_tls_size = tls_size;
#endif
}

uptr GetTlsSize() {
  return g_tls_size;
}

#if defined(__x86_64__) || defined(__i386__)
// sizeof(struct thread) from glibc.
// There has been a report of this being different on glibc 2.11 and 2.13. We
// don't know when this change happened, so 2.14 is a conservative estimate.
#if __GLIBC_PREREQ(2, 14)
const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1216, 2304);
#else
const uptr kThreadDescriptorSize = FIRST_32_SECOND_64(1168, 2304);
#endif

uptr ThreadDescriptorSize() {
  return kThreadDescriptorSize;
}

// The offset at which pointer to self is located in the thread descriptor.
const uptr kThreadSelfOffset = FIRST_32_SECOND_64(8, 16);

uptr ThreadSelfOffset() {
  return kThreadSelfOffset;
}

uptr ThreadSelf() {
  uptr descr_addr;
#ifdef __i386__
  asm("mov %%gs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
#else
  asm("mov %%fs:%c1,%0" : "=r"(descr_addr) : "i"(kThreadSelfOffset));
#endif
  return descr_addr;
}
#endif  // defined(__x86_64__) || defined(__i386__)

void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
                          uptr *tls_addr, uptr *tls_size) {
#ifndef SANITIZER_GO
#if defined(__x86_64__) || defined(__i386__)
  *tls_addr = ThreadSelf();
  *tls_size = GetTlsSize();
  *tls_addr -= *tls_size;
  *tls_addr += kThreadDescriptorSize;
#else
  *tls_addr = 0;
  *tls_size = 0;
#endif

  uptr stack_top, stack_bottom;
  GetThreadStackTopAndBottom(main, &stack_top, &stack_bottom);
  *stk_addr = stack_bottom;
  *stk_size = stack_top - stack_bottom;

  if (!main) {
    // If stack and tls intersect, make them non-intersecting.
    if (*tls_addr > *stk_addr && *tls_addr < *stk_addr + *stk_size) {
      CHECK_GT(*tls_addr + *tls_size, *stk_addr);
      CHECK_LE(*tls_addr + *tls_size, *stk_addr + *stk_size);
      *stk_size -= *tls_size;
      *tls_addr = *stk_addr + *stk_size;
    }
  }
#else  // SANITIZER_GO
  *stk_addr = 0;
  *stk_size = 0;
  *tls_addr = 0;
  *tls_size = 0;
#endif  // SANITIZER_GO
}

void AdjustStackSizeLinux(void *attr_) {
  pthread_attr_t *attr = (pthread_attr_t *)attr_;
  uptr stackaddr = 0;
  size_t stacksize = 0;
  pthread_attr_getstack(attr, (void**)&stackaddr, &stacksize);
  // GLibC will return (0 - stacksize) as the stack address in the case when
  // stacksize is set, but stackaddr is not.
  bool stack_set = (stackaddr != 0) && (stackaddr + stacksize != 0);
  // We place a lot of tool data into TLS, account for that.
  const uptr minstacksize = GetTlsSize() + 128*1024;
  if (stacksize < minstacksize) {
    if (!stack_set) {
      if (common_flags()->verbosity && stacksize != 0)
        Printf("Sanitizer: increasing stacksize %zu->%zu\n", stacksize,
               minstacksize);
      pthread_attr_setstacksize(attr, minstacksize);
    } else {
      Printf("Sanitizer: pre-allocated stack size is insufficient: "
             "%zu < %zu\n", stacksize, minstacksize);
      Printf("Sanitizer: pthread_create is likely to fail.\n");
    }
  }
}

#if SANITIZER_ANDROID
uptr GetListOfModules(LoadedModule *modules, uptr max_modules,
                      string_predicate_t filter) {
  return 0;
}
#else  // SANITIZER_ANDROID
typedef ElfW(Phdr) Elf_Phdr;

struct DlIteratePhdrData {
  LoadedModule *modules;
  uptr current_n;
  bool first;
  uptr max_n;
  string_predicate_t filter;
};

static int dl_iterate_phdr_cb(dl_phdr_info *info, size_t size, void *arg) {
  DlIteratePhdrData *data = (DlIteratePhdrData*)arg;
  if (data->current_n == data->max_n)
    return 0;
  InternalScopedBuffer<char> module_name(kMaxPathLength);
  module_name.data()[0] = '\0';
  if (data->first) {
    data->first = false;
    // First module is the binary itself.
    ReadBinaryName(module_name.data(), module_name.size());
  } else if (info->dlpi_name) {
    internal_strncpy(module_name.data(), info->dlpi_name, module_name.size());
  }
  if (module_name.data()[0] == '\0')
    return 0;
  if (data->filter && !data->filter(module_name.data()))
    return 0;
  void *mem = &data->modules[data->current_n];
  LoadedModule *cur_module = new(mem) LoadedModule(module_name.data(),
                                                   info->dlpi_addr);
  data->current_n++;
  for (int i = 0; i < info->dlpi_phnum; i++) {
    const Elf_Phdr *phdr = &info->dlpi_phdr[i];
    if (phdr->p_type == PT_LOAD) {
      uptr cur_beg = info->dlpi_addr + phdr->p_vaddr;
      uptr cur_end = cur_beg + phdr->p_memsz;
      cur_module->addAddressRange(cur_beg, cur_end);
    }
  }
  return 0;
}

uptr GetListOfModules(LoadedModule *modules, uptr max_modules,
                      string_predicate_t filter) {
  CHECK(modules);
  DlIteratePhdrData data = {modules, 0, true, max_modules, filter};
  dl_iterate_phdr(dl_iterate_phdr_cb, &data);
  return data.current_n;
}
#endif  // SANITIZER_ANDROID

}  // namespace __sanitizer

#endif  // SANITIZER_LINUX